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OBJECTIVE MEASUREMENT OF SURFACE DEFECTS AND CRACKS

Road surface condition measurement

Thomas Lundberg, VTI

Christian Glantz, Ramböll

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OUTLINE

• Why this project is done

• Equipment tested

• Reference for comparison

• Selection of sections

• What is done in Europe?

• Some results

• Findings and further work

BACKGROUND

Rutting

IRI

Edge depth

Other

In the Nordic countries the climate has a quite large effect on the type of damages

In Sweden around 50 % of the maintenance is done because of other reasons than unevenness (rut depth, IRI and edge depth)

Bleeding

Potholes

Raveling

AgingCracking

PURPOSE WITH THIS PROJECT

MAINTENANCE STANDARD IN SWEDEN

• In Sweden there is a Maintenance Standard with criteria’s/limits for IRI, Rut depth and Edge depth that is used to select maintenance objects

• The long-term goal for the Transport Administration is to include limits for cracks and surface damages in the Maintenance Standard

I. Can stretches that require maintenance due to surface damages be detected with laser based scanning technique?

II. Is it possible for the Transport Administration to use the technique on a network level for selecting objects for maintenance action?

III. Draft for a method (depending on result from I and II)

Client: Swedish Transport AdministrationCooperation between VTI and Ramboll

OBJECTS MEASURED IN THE PROJECT

Län Vägnummer Objekt Längd TRV Orsak till åtgärd TRV Orsak till åtgärd, motiv

M 6 Tpl Lockarp-Tpl Fredriksberg, K1 RF 5080 UH-Std Spår Stensläpp

M 19 Degeberga 2030 UH-Std IRI

M 108 Haglösa-Klörup 4320 UH-Std Spår Behov nytt slitlager

M 108 Cpl Tungan-Södervidinge 2350 UH-Std Flera

M 755 Skivarp-Skurup 4440 Def./kanth/ojmn Sliten, behov nytt slitlager

M 816 Holmeja-Cpl Sturup 4680 Def./kanth/ojmn Behov nytt slitlager

M 913 Borgeby-Tpl Flädie 2650 Ytskador, ålder Behov nytt slitlager

M 1054 Hörups k:a-Hannas 3570 Ytskador, ålder Behov nytt slitlager

M 1179 Dösjebro-Annelöv 1760 Ytskador, ålder Slitlagerbehov

M 1274 Reslöv-Trollenäs 3420 Ytskador, ålder Behov nytt slitlager

M 102 Dalby - Lund 3470 Ramböll Sprickor, stensläpp i mindre omfattn.

M 1136 Löddeköpinge - Barsebäckshamn 4190 Ramböll Fåtal sprickor

M 17 Förbifart Marieholm LTPP 4200 Ramböll Sprickor, stensläpp i mindre omfattn.

M 887 Bjällerup - St Råby 4490 Ramböll Div. ytskador

M 1135 Löddeköpinge - Vikhög 3883 Ytskador, ålder Behov nytt slitlager

E 758 Hovetorp-Beatelund 2240 Def./kanth/ojmn def./kanthäng

E 134 Utfart mot Åtvid 3000 Ytskador, ålder ålder

E 210 Höstrum- ST Anna 6852 Ytskador, ålder ålder

E 503 F-Länsgräns - Ödeshög 5000 Ytskador, ålder ytning abb

E 610 Haraldsbo-Skeda Udde 5000 Ytskador, ålder ytbeläggningar abb justeringar

E 796 Linghem 1262 Inga skador

E 705/688 Arnebo 4800

W 951 Genom Färnäs 3069 Stensläpp ABSen torr samt sten har börjat plocka.

W 908 Smedsbo - Helgsjön 4999 Ytskador, ålder Ytbehandling, MJOG 1997.

W 1001 Vsk 70-Våmhus 4972 Ytskador, ålder Beläggning släpper, behöver tätas med ytbehandling.

W 1002 Orsa - Fryksås 5039 Ytskador, ålder Fortsätta behålla vägens fina yta.

W 1025 Evertsberg - Oxberg 6047 Ytskador, ålder Sprickor/skador. Åtgärd för att klara vägen tills den byggs om.

U 252 Hallstahammar LTPP 898

W 69 Sörbo LTPP 1854

SELECTION OF OBJECTS

• The objects were in the plan for maintenance within three years due to surface damages

• Some objects were chosen by Ramboll and VTI

• Different roads and asphalt types

• Different types of surface damages

Wide cracks Cracks/raveling

Raveling

Minor roads Major roads

LASER SCANNING

• All roads were measured with Ramboll’s Pavemetrics system (LCMS-1)

• Each road was measured in both directions

• Each lane was measured twice to study repeatability

• The measurement vehicle was placed in the middle of the lane so both road markings were included in the data (if possible)

REFERENCE METHOD

20 m

• Visual inspection from vehicle equipped odometer

• The surface damages was graded in four (0-3) levels per 20 m:

• Undamaged [0]

• Slightly damaged (no directly need for maintenance) [1]

• Spread out damages (need for maintenance) [2]

• Severe and spread out damages (directly need for maintenance) [3]

• The gradation was a combination of spreading and severity

STRATEGIES IN DIFFERENT COUNTRIES Survey, four questions was sent to a selected number of people across Europe.

(10 countries answered)

1. Is it mandatory to use a scanning laser technique or to get a high-resolution

transverse profile to calculate transverse unevenness?

a. What is the requirement for the point density in the transverse direction?

2. Do you measure cracks?

a. If you do, what technique is used?

b. If you do, is it used for maintenance planning?

3. Do you measure surface defects?

a. If you do, what technique is used?

b. If you do, which defects do you measure?

c. If you do, is it used for maintenance planning?

4. Do you have references to any documents we could refer to?

STRATEGIES IN DIFFERENT COUNTRIES –CRACK MEASUREMENT

STRATEGIES IN DIFFERENT COUNTRIES –CRACKS USED FOR MAINTENANCE PLANNING

Objective method could be either ”LCMS” or texture

STRATEGIES IN DIFFERENT COUNTRIES –MEASUREMENT OF SURFACE DEFECTS

STRATEGIES IN DIFFERENT COUNTRIES –MEASUREMENT OF SURFACE DEFECTS

Examples of surface defects

measured

(most common at the top)

• Raveling

• Pothole

• Patching

• Local Roughness

• Homogeneity

• Frost heave

SURFACE DEFECTS IN THIS STUDY

• We have concentrated on cracks and raveling in this study

• We have not looked at other defects, mainly because

there were not enough sections with other defects

• Not analyzed from LCMS,

Pick out, Pothole, Bleeding

RAVELING

CRACKS

ALLIGATOR CRACKS

MEASURE USED – FROM LCMS

• Percentage of squares (0.25 m)

with a defect

• E.g.

A section of total 1000 squares

where 10 squares have a

defect will get the value 1 %

ZONE1 ZONE2 ZONE4ZONE3

1

1 1 1

1 1 1 1

1 1 1

1 1 1

1 1 1

1 1

1 1 1

1 1

1 1

1 1 1 1

1 1 1 1

1 1 1

1 1 1 1

1 1

1

ZONE1 ZONE2 ZONE3 ZONE4

Transverse

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REPEATABILITY – CRACKS –AVERAGE PER SECTION ( A TOTAL OF 47 SECTIONS)

Good repeatability

If you check the

repeatability of 100 m

section → r=0.93

REPEATABILITY – RAVELING –AVERAGE PER SECTION

Acceptable

repeatability

If you check the

repeatability of 100 m

section → r=0.89

COMPARISON, LCMS AND VISUAL INSPECTION (VI)

• Difficult to compare two different methods

• We have calculated two different indexes from

a. cracks and alligator cracks from VI

b. cracks from LCMS-measurement.

Consideration taken to severity and amount of cracks.

• An average of the index is calculated per section

• The sections are ranked from the worst to the best according to the index

• A good match would be if the objective and subjective ranking is equal or almost

equal

• (Ranking is dangerous to use – small differences in the index can lead to big

differences in rank)

Section VI LCMS

705ar21 1 30

705ar11 2 21

019de11 3 2

019de21 4 18

1002or21 5 6

1002or11 6 4

COMPARISON, LCMS AND VISUAL INSPECTION –TOP 6 RANKED SECTIONS WITH THE WORST CONDITION, ACCORDING VI(47 SECTIONS)

Some section have good agreement

and some don’t

COMPARISON, LCMS AND VISUAL INSPECTION –FINDINGS

• At some sections the LCMS system detects cracks almost to perfection.

• At sections with a rough texture (SMA16), especially sections with raveling, the

system interpreter the texture (raveling) as cracks.

CRACKS – A GOOD EXAMPLE

CRACKS – INTERPRETS THE SURFACE STRUCTURE AS CRACKS

OTHER FINDINGS

• Raveling has also good and not so good examples when comparing with VI.

• Changing the settings in the analysis software from Pavemetrics can do a lot

with the results, (1. minimum length of crack to use, 2. do not detect cracks at

areas with a raveling index greater than X).

• In the study we have tested to support the LCMS system by using MPD,

megatexture and localized roughness. It gives promising results compared with

VI for surface defects.

• We have tested two alternative systems for crack measurement that gives

cracks in the same part of the road as LCMS, but it’s only tested at a few

sections.

• Next year (2020) the Transport Administration will start collecting cracks and

Ramböll will be the provider.

THE CHALLENGE FOR THE NEXT YEARS

• Increase the conformity of an automated objective method and VI.

• Find the software settings to get an objective system that can be used at

different pavements in different conditions in Sweden.

• Could MPD, megatexture and localized roughness be used to support an

objective system for surface defects?

• Decide whether using a surface-defect-index or data directly from an objective

system.

• After selecting a method, set threshold values for a maintenance standard,

regarding cracks and surface defects.

THANK YOU FOR YOUR ATTENTION,

Thomas Lundberg, thomas.lundberg@vti.se

Christian Glantz, christian.glantz@ramboll.se

SURFACE DEFECTS – SWEDENPOTHOLE BLEEDING RAVELING/

AGED BITUMEN

PATCHES

SURFACE DEFECTS – SWEDEN

ALLIGATOR CRACKS

CRACKS

MATERIAL LOSS/

AGED BITUMEN